Re: [Chicken-users] New immediate values (was: DBI)

[Tobia Conforto]

felix winkelmann wrote:
> > (define sql-null (new-immediate-value))
> > (define (sql-null? x) (eq? x sql-null))
> >
> > With the certainty that sql-null won't be eq? to anything else at  
> > all, won't be a list, a record, nothing at all except itself.  I  
> > think this could have a few uses.
>
> It would probably have uses, but what would you gain? All you need  
> is a distinct unique object:
>
> (define sql-null (gensym 'sql-null))


This is still a symbol.

People are using (void) because it's nothing but (void), that is, all  
standard predicates (symbol?, pair?, number?, string?...) return #f.   
Only its own predicate returns #t.


Tobia